Vitamin c causes kidney stones
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Vitamin C and Kidney Stones: Analyzing the Risk
Introduction to Vitamin C and Kidney Stones
Vitamin C, also known as ascorbic acid, is a vital nutrient known for its antioxidant properties and role in collagen synthesis. However, its potential link to kidney stone formation has been a subject of research and debate. This article synthesizes findings from multiple studies to understand whether vitamin C intake, particularly in high doses, contributes to the risk of kidney stones.
High-Dose Vitamin C and Increased Risk in Men
Several studies have indicated that high-dose vitamin C supplementation is associated with an increased risk of kidney stones in men. A large cohort study involving 156,735 women and 40,536 men found that while total and supplemental vitamin C intake was significantly associated with a higher risk of kidney stones in men, it was not in women . This study highlighted that men consuming 1,000 mg/day or more of supplemental vitamin C had a higher hazard ratio (HR) for kidney stones compared to those who did not take supplements .
Similarly, another study focusing on Swedish men reported a twofold increased risk of kidney stones with vitamin C supplementation. Men who took fewer than seven ascorbic acid tablets per week had a relative risk (RR) of 1.66, while those who took seven or more tablets had an RR of 2.23 . This study emphasized that the risk was specific to vitamin C supplements and not dietary vitamin C intake.
Mechanisms Behind Vitamin C-Induced Kidney Stones
The formation of kidney stones, particularly calcium oxalate stones, is influenced by various factors, including the excretion of oxalate in urine. Vitamin C can be metabolized into oxalate, which then contributes to stone formation. Research has shown that high doses of vitamin C increase urinary oxalate levels, thereby elevating the risk of kidney stones 245.
A study investigating the biochemical mechanisms found that high-dose vitamin C intake led to increased oxalate levels both intracellularly and extracellularly, promoting calcium oxalate crystal formation in the kidneys . This study also identified a pathway involving androgen receptors (AR) and miR-182, which regulates oxalate biosynthesis from vitamin C, further linking high-dose vitamin C to kidney stone formation .
Gender Differences in Risk
The risk of kidney stones associated with vitamin C intake appears to differ between men and women. While multiple studies have confirmed the increased risk in men, the same has not been observed in women. For instance, a study involving 85,557 women found no significant association between high vitamin C intake and kidney stone formation . This gender difference may be due to variations in metabolism and hormonal influences.
Dietary Vitamin C vs. Supplements
It is important to distinguish between dietary vitamin C and supplemental vitamin C. Most studies have found that dietary vitamin C intake does not significantly increase the risk of kidney stones. The risk is primarily associated with high-dose supplements. For example, a study noted that dietary vitamin C intake was not linked to kidney stones in either men or women, whereas supplemental intake was a risk factor for men 13.
Conclusion
In summary, high-dose vitamin C supplementation is associated with an increased risk of kidney stones in men, but not in women. This risk is primarily due to the conversion of vitamin C to oxalate, which contributes to stone formation. While dietary vitamin C does not pose the same risk, individuals, especially men, should be cautious with high-dose vitamin C supplements. Further research is needed to fully understand the mechanisms and to explore potential preventive measures for those at risk.
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